1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of preventing a ground clip from making contact with a display unit due to a deformation of the ground clip that is combined with an end of a mold frame to ground a printed circuit board to a top chassis.
2. Description of the Related Art
Recently, an information process device such as a computer has been rapidly improved as the information technology industry has been developed. In addition, this technological development has affected an improvement of a monitor device displaying information output from the information process device.
The aforementioned monitor device generally is divided into a cathode ray tube type of monitor device, using a characteristic of a cathode ray tube, and a liquid crystal display unit type of monitor device, applying physical and optical characteristics of liquid crystals. The liquid crystal display unit type of the monitor device has characteristics of being small in size and light in weight, and less consumption power. Accordingly, the liquid crystal display unit type of the monitor device is widely used as a display device of a lap-top top computer, a monitor of a desk-top computer and a monitor of a high-quality television receiver.
FIG. 1 is an exploded perspective view schematically showing the conventional liquid crystal display device and FIG. 2 is a plan view of a position of a ground clip for grounding a printed circuit board to a top chassis of the liquid crystal display device shown in FIG. 1. Also, FIGS. 3 and 4 show a combination construction of the liquid crystal display device shown in FIG. 1.
Referring to FIG. 1, the liquid crystal display device 100 has a liquid crystal display module 130 for displaying images when image signals are applied thereto, and front case 110 and rear case 120 for receiving the liquid crystal display module 130. The liquid crystal display module 130 includes a display unit 170 having a liquid crystal display panel for showing the images and a backlight assembly 150 for supplying a light to the display unit 170.
The display unit 170 has a liquid crystal display panel 171, a data side printed circuit board 176, a gate side printed circuit board 175, a data side tape carrier package 178 and a gate side tape carrier package 174.
The liquid crystal display panel 171 includes a thin film transistor board 172, a color filter board 173 and liquid crystal (not shown).
The thin film transistor board 172 is a transparent glass board on which the thin film transistors are formed in a matrix shape. Data lines are respectively connected with source terminals of the thin film transistors and gate lines are connected with gate terminals of the thin film transistors. Furthermore, pixel electrodes are respectively formed at drain terminals of the thin film transistors, which are made of a transparent conductive material such as Indium Tin Oxide (ITO).
The color filter board 173 is provided to face towards the thin film transistor board 172. RGB pixels are formed on the color filter board 173 by means of a thin film process, which presents a predetermined color while the light passes through the color filter board 173. Common electrodes made of ITO are coated on the front surface of the color filter board 173.
When the power source is applied to the gate terminals and to the source terminals of the transistors on the thin film transistor board 172, to turn on the thin film transistors, an electric field is created between the pixel electrodes of the thin film transistor board 172 and the common electrodes of the color filter board 173. The electric field changes the array angle of liquid crystal, which is injected between the thin film transistor board 172 and the color filter board 173. This changes the transmissivity of the light and shows the desired pixel images.
Meanwhile, a driving signal and a timing signal are applied to the gate lines and to data lines of the thin film transistors in order to control the array angle of the liquid crystal and the time of arraying the liquid crystal in the liquid crystal display panel 171. As shown in FIG. 1, the data side tape carrier package 178, which is made of flexible circuit boards, is attached to the source portion of the liquid crystal display panel 171 to determine a data driving signal timing. On the other hand, the gate side tape carrier package 174 is attached to the gate portion of the liquid crystal display panel 171 for a gate driving signal timing.
The data side printed circuit board 176 and the gate side printed circuit board 175, which respectively apply the driving signal to the gate line and to the data line as soon as receiving image signals input from outside of the liquid crystal display panel 171, makes contact with the data side tape carrier package 178 for the data line and the gate side tape carrier package 174 for the gate line in the liquid crystal display panel 171, respectively. A source portion is formed on the data side printed circuit board 176 in order to receive the image signals from an information process device (not shown) such as a computer, etc. and then to provide the gate driving signal for the gate line of the liquid crystal display panel 171. Also, a gate portion is formed on the gate side printed circuit board 175 to provide the gate driving signal to the gate lines of the liquid crystal display panel 171. That is, the data side printed circuit boards 176 and the gate side printed circuit board 175 generate and apply the gate driving signal and the data signal for driving the liquid crystal display device. They also generate a plurality of timing signals for applying the gate driving signal and the data signal to the gate lines and the data lines of the liquid crystal display panel 171, so as to provide the gate driving signal through the gate side tape carrier package 174 to the gate lines of the liquid crystal display panel 171 and to supply the data signal through the data side tape carrier package 178 to the data lines of the liquid crystal display panel 176.
A backlight assembly 150 is provided under the display unit 170 to uniformly supply the light to the display unit 170. The backlight assembly 150 includes a lamp unit 160, which is disposed at an end of the liquid crystal display module 130, for generating the light, a light guide plate 152 for guiding the light emitted from the lamp unit 160 toward the display unit 170 and changing a pathway of the light, a plurality of optical sheets 153 for adjusting a brightness of the light transmitted from the light guide plate 152 uniformly and a light reflecting plate 151 that is provided under the light guide plate 152 for reflecting the light leaking from the light guide plate 152 so as to improve the efficiency of the light.
The display unit 170 and the backlight assembly 150 are supported by a mold frame 131, that receives the light reflecting plate 151 and is used as a receiving container, and a top chassis 140 is provided to prevent the display unit 171 from departing from the mold frame 131.
As shown in FIG. 2, a ground clip 133 is combined to an end of the mold frame 131 that receives the display unit 171 in order to ground the data side printed circuit board 176. The ground clip 133 electrically connects the data side printed circuit board 176 to the top chassis 140.
Referring to FIG. 3, the mold frame 131 receives the light reflecting plate 151, the light guide plate 152 and the optical sheets 153 in that order. The display unit 170 is placed on the optical sheets 153 so as to partially overlap the mold frame 131. The ground clip 133 is mounted to enclose an end of the mold frame 131. The ground clip 133 extends from an upper surface of the end of the mold frame 131 to the printed circuit board 176. A portion of the ground clip 133, which is bent to a rear surface of the mold frame 131, contacts the data side printed circuit board 176. The display unit 170 is fixed to the mold frame 131 by the top chassis 140 faced towards and combined with the mold frame 131. The top chassis 140 contacts the ground clip 133 at a side of the mold frame 131, making the top chassis 140 being electrically connected with the data side printed circuit board 176 through the ground clip 133.
However, the mold frame 131 is typically made of a resin and flexes when an outer force is applied to the mold frame 131. As shown in FIG. 4A, when the one end, on which the ground clip 133 is mounted, and the other end of the mold frame 131 are pressed by a force P, a bottom surface of the mold frame 131 is flexed as shown by a reference symbol A. This forms a gap between the mold frame 131 and the backlight assembly received in the mold frame 131. As a result, while being pushed into the mold frame 131, one end of the ground clip 133 makes contact with a ITO electrode of the color filter board 173 of the liquid crystal display panel 171. The reference numeral 172a is a polarization plate for the thin film transistor board 172, and the reference numeral 173a is a polarization plate for the color filter board 173. As shown in FIG. 4B, when the thin film transistor board 172 is formed to be longer than the color filter board 173, the ground clip 133 makes electrical contact with the liquid crystal display panel 171 as being climbed above an upper portion of the thin film transistor board 172 by the force applied to the ground clip 133. That is, while the upper portion of the ground clip 133 departs from an upper surface of the mold frame 131, the ground clip 133 makes electrical contact with the liquid crystal display panel 171 as shown by reference symbols B and C in FIGS. 4A and 4B, respectively. Accordingly, there is a problem in that the data side printed circuit board 176, the liquid crystal display panel 171, the top chassis 140 and the ground clip 133 are subjected to form an electrical short circuit.
The present invention has been made to solve the aforementioned problem, and accordingly it is an object of the present invention to provide a liquid crystal display device capable of preventing a ground clip from connecting with a display unit due to a deformation of the ground clip that is combined with an end of a mold frame to ground a printed circuit board to a top chassis.
To achieve the object of the present invention, a liquid crystal display device comprises a display unit for displaying an image, a mold frame for receiving the display unit, a printed circuit board mounted on a rear surface of the mold frame for controlling an operation of the display unit and a top chassis faced towards and combined with the mold frame for guiding a position of the display unit.
A grounding clip for grounding the printed circuit board to the top chassis is combined with an end of the mold frame. The mold frame has a projection, which is formed on an upper surface of the end of the mold frame, in order to prevent the clip from making electrical contact with the display unit. The grounding clip is disposed to enclose the end of the mold frame in such a manner of extending from the upper surface of the end of the mold frame, on which the projection is formed, to the printed circuit board. A gap between the display unit and the projection is narrower than a gap between the display unit and the grounding clip.
The mold frame further comprises a projection formed on an upper surface of the other end opposite to the one end thereof. At least one projection is formed on the upper surfaces of both ends of the mold frame. The projection fixes the display unit to the mold frame so as to prevent a movement of the display unit.
According to the liquid crystal display device of the present invention, a guide projection is formed to be adjacent to the grounding clip combined to the one end of the mold frame. A gap between the guide projection and the liquid crystal display panel is narrower than a gap between the liquid crystal display panel and the grounding clip. Accordingly, even though the mold frame flexes due to a force applied thereto, it is possible to prevent a deformation of the grounding clip. As a result, it is possible to prevent the grounding clip from connecting with the liquid crystal display panel and forming an electrical short circuit.